Neverless mostly reasons of error 800B0100 are caused corrupted components as I said before and easy methods will never work examples similar to you: Vista SP2 fails to install, error trust_e_nosignature (0x800b0100) Impossible to install new Windows security Updates (error 800B0100 and 80246007) - Vista Forums
how to fix:
1.Empty folder C:\Windows\Logs\CBS
next download files attached to post and unpack them anywhere
2.Navigate to C:\Windows\Servicing\Packages
,takeownership of this folder and add your account to have full control
3.Copy my files to this folder -if you have already any file then replace it.
4.Remove your account from permissions to Packages folder
5.Restore ownership of Packages folder back to "NT Service\TrustedInstaller"
6.Again try install hotfixes
helpful links (please read them) Take Ownership of file - Vista Forums TrustedInstaller - Restore as Owner - Vista Forums Folder Permissions - Vista Forums
If it still don't help again run Readiness Tool and attache to post new CheckSur.log file